Make FileDataSourceFactory an inner class

This is a proof of concept for cleanup we should do for all of
our DataSource implementations as we move toward stabilizing
parts of the API.

- Move all XDataSourceFactory classes to be inner classes.
- Remove chained constructors for XDataSourceFactory classes. Keep
  required args going through constructors. Use setters for the
  rest.
- Not applicable in this case, but we probably want to deprecate
  all but the no-arg method for instantiating eac XDataSource
  instance (with the all-arg method kept but with the intention
  of making it package private).

PiperOrigin-RevId: 274162076

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoApplication.java

@@ -28,7 +28,7 @@ import com.google.android.exoplayer2.offline.DownloaderConstructorHelper;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
-import com.google.android.exoplayer2.upstream.FileDataSourceFactory;
+import com.google.android.exoplayer2.upstream.FileDataSource;
 import com.google.android.exoplayer2.upstream.HttpDataSource;
 import com.google.android.exoplayer2.upstream.cache.Cache;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
@@ -165,7 +165,7 @@ public class DemoApplication extends Application {
     return new CacheDataSourceFactory(
         cache,
         upstreamFactory,
-        new FileDataSourceFactory(),
+        new FileDataSource.Factory(),
         /* cacheWriteDataSinkFactory= */ null,
         CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR,
         /* eventListener= */ null);

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloaderConstructorHelper.java

@@ -20,6 +20,7 @@ import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.upstream.DataSink;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DummyDataSource;
+import com.google.android.exoplayer2.upstream.FileDataSource;
 import com.google.android.exoplayer2.upstream.FileDataSourceFactory;
 import com.google.android.exoplayer2.upstream.PriorityDataSourceFactory;
 import com.google.android.exoplayer2.upstream.cache.Cache;
@@ -108,7 +109,7 @@ public final class DownloaderConstructorHelper {
     DataSource.Factory readDataSourceFactory =
         cacheReadDataSourceFactory != null
             ? cacheReadDataSourceFactory
-            : new FileDataSourceFactory();
+            : new FileDataSource.Factory();
     if (cacheWriteDataSinkFactory == null) {
       cacheWriteDataSinkFactory =
           new CacheDataSinkFactory(cache, CacheDataSink.DEFAULT_FRAGMENT_SIZE);

library/core/src/main/java/com/google/android/exoplayer2/upstream/FileDataSource.java

@@ -30,9 +30,7 @@ import java.io.RandomAccessFile;
 /** A {@link DataSource} for reading local files. */
 public final class FileDataSource extends BaseDataSource {
 
-  /**
-   * Thrown when IOException is encountered during local file read operation.
-   */
+  /** Thrown when a {@link FileDataSource} encounters an error reading a file. */
   public static class FileDataSourceException extends IOException {
 
     public FileDataSourceException(IOException cause) {
@@ -44,6 +42,32 @@ public final class FileDataSource extends BaseDataSource {
     }
   }
 
+  /** {@link DataSource.Factory} for {@link FileDataSource} instances. */
+  public static final class Factory implements DataSource.Factory {
+
+    @Nullable private TransferListener listener;
+
+    /**
+     * Sets a {@link TransferListener} for {@link FileDataSource} instances created by this factory.
+     *
+     * @param listener The {@link TransferListener}.
+     * @return This factory.
+     */
+    public Factory setListener(@Nullable TransferListener listener) {
+      this.listener = listener;
+      return this;
+    }
+
+    @Override
+    public FileDataSource createDataSource() {
+      FileDataSource dataSource = new FileDataSource();
+      if (listener != null) {
+        dataSource.addTransferListener(listener);
+      }
+      return dataSource;
+    }
+  }
+
   @Nullable private RandomAccessFile file;
   @Nullable private Uri uri;
   private long bytesRemaining;

library/core/src/main/java/com/google/android/exoplayer2/upstream/FileDataSourceFactory.java

@@ -17,28 +17,22 @@ package com.google.android.exoplayer2.upstream;
 
 import androidx.annotation.Nullable;
 
-/**
- * A {@link DataSource.Factory} that produces {@link FileDataSource}.
- */
+/** @deprecated Use {@link FileDataSource.Factory}. */
+@Deprecated
 public final class FileDataSourceFactory implements DataSource.Factory {
 
-  @Nullable private final TransferListener listener;
+  private final FileDataSource.Factory wrappedFactory;
 
   public FileDataSourceFactory() {
-    this(null);
+    this(/* listener= */ null);
   }
 
   public FileDataSourceFactory(@Nullable TransferListener listener) {
-    this.listener = listener;
+    wrappedFactory = new FileDataSource.Factory().setListener(listener);
   }
 
   @Override
   public FileDataSource createDataSource() {
-    FileDataSource dataSource = new FileDataSource();
-    if (listener != null) {
-      dataSource.addTransferListener(listener);
-    }
-    return dataSource;
+    return wrappedFactory.createDataSource();
   }
-
 }

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSourceFactory.java

@@ -18,7 +18,7 @@ package com.google.android.exoplayer2.upstream.cache;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.upstream.DataSink;
 import com.google.android.exoplayer2.upstream.DataSource;
-import com.google.android.exoplayer2.upstream.FileDataSourceFactory;
+import com.google.android.exoplayer2.upstream.FileDataSource;
 
 /** A {@link DataSource.Factory} that produces {@link CacheDataSource}. */
 public final class CacheDataSourceFactory implements DataSource.Factory {
@@ -49,7 +49,7 @@ public final class CacheDataSourceFactory implements DataSource.Factory {
     this(
         cache,
         upstreamFactory,
-        new FileDataSourceFactory(),
+        new FileDataSource.Factory(),
         new CacheDataSinkFactory(cache, CacheDataSink.DEFAULT_FRAGMENT_SIZE),
         flags,
         /* eventListener= */ null);